The Two Futures of HVAC Controls

Two futures are possible for HVAC controls. One is exciting; the other not so much so. In the exciting scenario, controls rapidly evolve so that, in just a few years, building controls have extensive self-commissioning, self-tuning, self-diagnostic and correction, and even self-configuring features. HVAC systems simply require components to be connected together with a short list of parameters set, and the system takes off from there—notifying the commissioning agent, contractor, engineer and/or operator if it is meeting its specified high-performance criteria, or, if it is not, what corrective steps are necessary.

Here’s how this would evolve. In my column in the December edition of Networked Controls Plus (bit.ly/relationalcontrol) I discussed multi-variable relational control, which can greatly improve performance, energy efficiency, and system stability. But relational control offers much more. This multivariable method of control provides an ideal platform for extension into a type of artificial intelligence called neural net control, which will begin a new era in building control.

Relational control allows the software designer to select a wide variety of system variables that may influence the optimal operation of a system. The multivariable relationships may be very basic, such as fluid mixing laws, or much more complex, such overall energy optimization via the equal marginal performance principle. The logical next step in HVAC control software development is software modules that will automatically discover other variables (and/or combination of variables) that will assist further in tuning, optimization, self-configuration, self-setup, and fault detection with prescribed corrective actions. It’s becoming universally clear that such widespread implementation of advanced building control could cut total energy consumed by our buildings by about half, while at the same time improving occupant comfort.

Research has already started on these new types of HVAC control software, but they remain largely absent from HVAC controls today. That’s because our industry holds onto its one-of-a-kind design and construction process in which the designer, after selecting equipment, develops a rudimentary control sequence that then goes through a tortuous process of being interpreted and made to work by others.

If the industry continues on this business-as-usual path, we’ll see a much less exciting future. Unfortunately, all too many industry players—including the very organizations that promote and encourage higher performance HVAC systems—seem oblivious to the problem. Many continue to promote the idea that if we could just develop, train and educate our industry to these new approaches, the archaic process we employ to design and implement HVAC systems could successfully advance them.

But it can’t. A lot of time and money have already been spent proving that point. For more than a decade a variety of groups and agencies have shown through research and case studies that applying advanced controls can produce high-performance buildings, but despite funding and incentives, almost none show any significant long-term performance improvement over similar standard-controlled systems. So, unless there is a real effort to change the process by which building HVAC systems are implemented and supported, building control design and implementation will remain the frustrating nightmare it is today and significantly higher- performing buildings though improved control will remain an elusive dream.

How can it change? One encouraging sign is the developing focus on accountability for long-term building performance. It’s not clear yet whether this path will be seen through correctly, but if it is the value of such advanced control software and the need to change the process will become apparent. Engineers will begin to understand that instead of developing crude sequences, their specification needs to focus on performance requirements along with ongoing verification and support. That’s when the evolution to the exciting future will really take flight. I urge all who are committed to improving energy and comfort performance in buildings to support this trend toward energy performance accountability and then participate in the exciting future controls will play in meeting the high performance goals.

I invite your thoughts, comments, and good ideas about this article. Please contact me at thc@hartmanco.com.

Thomas Hartman, PE, is principal of The Hartman Co., Georgetown, TX. He can be reached at 254/793-0120, or by e-mail at thc@hartmanco.co.